The operators of the San Onofre nuclear plant say they want to get experts this summer to reconsider the threats from earthquakes nearby.

That's in addition to a routine twice-yearly review, Caroline McAndrews, the plant's director of licensing, told state senators in an informational hearing in Sacramento Monday.

The goal, she said, is to "arrive at a consensus for uncertainties that exist in our area."

Workers at the 2,200-megawatt plant are focused on learning what they can from the crisis now underway at a Japanese nuclear plant following a magnitude 9.0 quake on March 11, she said.

San Onofre's twin reactors are designed to withstand .67g of ground movement. (That's movement with the force of 67 percent of the pull of the earth's gravity, equivalent to a 7.0 magnitude earthquake within five miles.)

But that's not the exact measure of the plant's vulnerability, she said.

That's because engineers factor in a safety margin to exceed what's expected.

The crisis at the Fukushima Dai-ichi nuclear plant in Japan has brought renewed attention to safety questions at nuclear plants around the country and the world.

California's two nuclear plants, San Onofre and Diablo Canyon, are both on the coast and near earthquake faults.

The companies that own and run them, Southern California Edison and Pacific Gas & Electric, say they are designed to deal with the threat of quakes and tsunamis.

San Onofre, for example, sits behind a 30-foot seawall, which McAndrews says is 7 feet higher than what the latest inundation maps indicate is needed.

But new faults have been found since they were built decades ago.

Edison disagrees with the conclusions from some geologists that connections to other faults off the Southern California coast increase the risk of an earthquake much bigger than previously predicted.

And it says that the size of a quake isn't the measure that matters.

"We need to separate a magnitude earthquake from ground motion of the plant," McAndrews said. "While there may be a large magnitude earthquake somewhere out at a fault line, the ground attenuates and dampens that effect."

In other words, how a quake feels depends not only on how strong it is, but on where you are when it hits you.

Sen. Christine Kehoe, D-San Diego, questioned McAndrews about what would happen if a quake bigger than a magnitude 7 were to strike nearby.

McAndrews couldn't say.

"I can't answer that number," she said. "We'd have to do specific analysis on the fragility of that equipment."

The crisis in Japan was caused in large part from damage from the quake and the tsunami to systems that cool the plant's reactors and spent nuclear fuel stored nearby.

McAndrews said there are several systems in place, including keeping diesel fuel and backup generators behind the 30-foot tsunami wall, to ensure that there is enough water available to keep the temperature of the reactors and the spent fuel under control.

San Diego gets about 20 percent of its electricity from San Onofre, which is located on the northern edge of Camp Pendleton in the North County. San Diego Gas & Electric owns 20 percent of the nuclear plant.